Earlier quoted context omitted.
If you are doing very high-performance numerical work, your choices¹ are Fortran, C, C++, or Julia. Julia is way more fun to program in than the other choices. Also, it has some properties² that make code re-use and re-combination especially easy. 1 https://www.hpcwire.com/off-the-wire/julia-joins-petaflop-cl... 2 https://arstechnica.com/science/2020/10/the-unreasonable-eff...
What's the argument against using R and dropping into RCpp for very limited tasks? I (helped) write a very widely used R modelling package and while I wasn't doing anything on the numerical side, we seemed to get great performance from this approach -- and workflow-wise it wasn't too dissimilar to 25 years ago where I had to occasionally drop in X86 assembly to speed up C code! (Not a hater of Julia at all, very much…
I've been impressed with Julia, but it's hard to beat 25 years of package development.